// Tencent is pleased to support the open source community by making RapidJSON available.
//
// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
//
// Licensed under the MIT License (the "License"); you may not use this file except
// in compliance with the License. You may obtain a copy of the License at
//
// http://opensource.org/licenses/MIT
//
// Unless required by applicable law or agreed to in writing, software distributed
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
// specific language governing permissions and limitations under the License.

#ifndef RAPIDJSON_FILEREADSTREAM_H_
#define RAPIDJSON_FILEREADSTREAM_H_

#include "stream.h"
#include <cstdio>

#ifdef __clang__
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(padded)
RAPIDJSON_DIAG_OFF(unreachable-code)
RAPIDJSON_DIAG_OFF(missing-noreturn)
#endif

RAPIDJSON_NAMESPACE_BEGIN

//! File byte stream for input using fread().
/*!
    \note implements Stream concept
*/
class FileReadStream
{
  public:
    typedef char Ch;    //!< Character type (byte).

    //! Constructor.
    /*!
        \param fp File pointer opened for read.
        \param buffer user-supplied buffer.
        \param bufferSize size of buffer in bytes. Must >=4 bytes.
    */
    FileReadStream(std::FILE *fp, char *buffer, size_t bufferSize) : fp_(fp), buffer_(buffer), bufferSize_(bufferSize), bufferLast_(0), current_(buffer_), readCount_(0), count_(0), eof_(false)
    {
      RAPIDJSON_ASSERT(fp_ != 0);
      RAPIDJSON_ASSERT(bufferSize >= 4);
      Read();
    }

    Ch Peek() const
    {
      return *current_;
    }
    Ch Take()
    {
      Ch c = *current_;
      Read();
      return c;
    }
    size_t Tell() const
    {
      return count_ + static_cast<size_t>(current_ - buffer_);
    }

    // Not implemented
    void Put(Ch)
    {
      RAPIDJSON_ASSERT(false);
    }
    void Flush()
    {
      RAPIDJSON_ASSERT(false);
    }
    Ch *PutBegin()
    {
      RAPIDJSON_ASSERT(false);
      return 0;
    }
    size_t PutEnd(Ch *)
    {
      RAPIDJSON_ASSERT(false);
      return 0;
    }

    // For encoding detection only.
    const Ch *Peek4() const
    {
      return (current_ + 4 <= bufferLast_) ? current_ : 0;
    }

  private:
    void Read()
    {
      if (current_ < bufferLast_)
        ++current_;
      else if (!eof_)
        {
          count_ += readCount_;
          readCount_ = std::fread(buffer_, 1, bufferSize_, fp_);
          bufferLast_ = buffer_ + readCount_ - 1;
          current_ = buffer_;

          if (readCount_ < bufferSize_)
            {
              buffer_[readCount_] = '\0';
              ++bufferLast_;
              eof_ = true;
            }
        }
    }

    std::FILE *fp_;
    Ch *buffer_;
    size_t bufferSize_;
    Ch *bufferLast_;
    Ch *current_;
    size_t readCount_;
    size_t count_;  //!< Number of characters read
    bool eof_;
};

RAPIDJSON_NAMESPACE_END

#ifdef __clang__
RAPIDJSON_DIAG_POP
#endif

#endif // RAPIDJSON_FILESTREAM_H_
